Strengthened blade tape measure

ABSTRACT

A strengthened blade tape measure includes a tape casing, a retraction unit, and a ruler blade, having an inner end attached to the retraction unit and an outer end stopped at a guiding opening of the tape casing, adapted to slidably fold between a storage position and a measuring position. In which, at the storage position, the ruler blade is retracted to receive in the tape casing in a coil flattened configuration manner via the retraction unit, and at the measuring portion, the outer end of the ruler blade is slidably pulled to extend the ruler blade in a concave-convex configuration out of the tape casing through the guider opening, wherein the ruler blade is capable of standing out from the tape casing with a measuring length at least 10 feet in a self-sustaining manner so as to prevent the ruler blade from buckling by its own weight.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part application ofnon-provisional application, application Ser. No. 10/633,393, filed Jul.31, 2003.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a tape measure, and more particularlyto a strengthened blade retractable tape measure, wherein the rulerblade, having a predetermined curvature, is adapted to rigidly extend atleast 10 feet from the tape casing in a self-sustaining manner withoutbuckling by its own weight, so as to substantially lengthen themeasuring distance along the measuring blade.

2. Description of Related Arts

Retractable tape measures have been commonly used in commercial. Aconventional retractable tape measure generally comprises a tape casing,a retractable reel assembly rotatably supported in the tape casing, anda ruler blade having an inner end attached to the retractable reelassembly such that the ruler blade is adapted to fold in the tape casingin a coil manner and to extend from the tape casing for length measuringpurpose.

There are two major features of the retractable tape measure forprofessional use, especially for construction. One of the features ofsuch retractable tape measure is to provide the ruler blade having apredetermined length to lengthen the measuring distance along the rulerblade. Another feature of the retractable tape measure is to provide theruler blade that the ruler blade must be rigid enough to self-sustainingmanner when the ruler blade is extended from the tape casing. Therefore,the user is able to self-operate the retractable tape measure to measurethe distance. In other words, the size and the weight of the retractabletape measure is not the most important concern for the professionals.

In order to accomplish the above features of the retractable tapemeasure, the dimension of the ruler blade must be configured. The widthof the ruler blade can be substantially increased for enhancing theself-sustaining support of the ruler blade. However, the length of theruler blade will be shortened to remain the weight thereof constantly.Alternatively, the curvature of the ruler blade can be increased toenhance the self-sustaining ability thereof. However, the ruler bladecannot be smoothly retracted back to the tape casing.

Accordingly, U.S. Pat. No. 6,324,769, owned by Murray, generallysuggests a tape measure comprising a ruler blade having a width in theflattened configuration thereof having a dimension within the range of1.10″-1.5″, a height in the concave-convex configuration thereof havinga dimension within the range of 0.25″-0.40″, and a thickness in eitherconfiguration thereof having a dimension within the range of0.0045″-0.0063″, such that the ruler blade is capable of standing outfrom the tape casing with a measuring length at least 10.5 feet.Therefore, the modification and improvement of the ruler blade should beconsidered as one of the important subject matter of the retractabletape measure to enhance the practice use thereof.

SUMMARY OF THE PRESENT INVENTION

A main object of the present invention is to provide a strengthenedblade tape measure, wherein the ruler blade, having a predeterminedcurvature, is adapted to rigidly extend at least 10 feet from the tapecasing in a self-sustaining manner without buckling by its own weight,so as to substantially lengthen the measuring distance along themeasuring blade.

Another object of the present invention is to provide a strengthenedblade tape measure, wherein the curvature of the ruler blade does notaffect the retraction operation of the tape measure via the retractionunit such that the ruler blade with its curvature is adapted to smoothlyslide out from the tape casing for measuring purpose and to smoothlyslide back to the tape casing for storage.

Another object of the present invention is to provide a strengthenedblade tape measure which does not require altering its originalstructural design to incorporate with the ruler blade so as to minimizethe manufacturing cost of the tape measure. In other words, the rulerblade is adapted to incorporate the conventional tape casing withoutaltering the original structure thereof.

Another object of the present invention is to provide a strengthenedblade tape measure, wherein no expensive or complicated structure isrequired to employ in the present invention in order to achieve theabove mentioned objects. Therefore, the present invention successfullyprovides an economic and effective solution not only for providing arigid configuration to support the ruler blade in a self-sustainingmanner but also for enhancing the measuring distance of the ruler bladeextending out from the tape casing.

Accordingly, in order to accomplish the above objects, the presentinvention provides a strengthened blade tape measure, comprising:

-   -   a tape casing having a receiving cavity and a guider opening        communicating with the receiving cavity;    -   a retraction unit supported in the receiving cavity; and    -   a ruler blade, having an inner end attached to the retraction        unit and an outer end stopped at the guiding opening, adapted to        slidably fold between a storage position and a measuring        position, wherein at the storage position, the ruler blade is        retracted to receive in the receiving cavity in a coil flattened        configuration manner via the retraction unit, and at the        measuring portion, the outer end of the ruler blade is slidably        pulled to extend the ruler blade in a concave-convex        configuration out of the receiving cavity through the guider        opening, the ruler blade having a width in the flattened        configuration thereof having a dimension within the range of        40-42 mm, a height in the concave-convex configuration thereof        having a dimension within the range of 9-12 mm, and a thickness        thereof having a dimension at least 11.5 mm-12.0 mm, such that        the ruler blade is capable of standing out from the tape casing        with a measuring length at least 10 feet in a self-sustaining        manner so as to prevent the ruler blade from buckling by its own        weight.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a strengthened blade tape measureaccording to a preferred embodiment of the present invention.

FIG. 2 is a sectional view of the strengthened blade tape measureaccording to the above preferred embodiment of the present invention.

FIG. 3 illustrates the dimensions of the ruler blade of the strengthenedblade tape measure in the concave-convex configuration according to theabove preferred embodiment of the present invention.

FIG. 4 illustrates the dimensions of the ruler blade of the strengthenedblade tape measure in the flattened configuration according to the abovepreferred embodiment of the present invention.

FIG. 5 illustrates the dimensions of the ruler blade and its alternativemodes according to the above preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2 of the drawings, a strengthened blade tapemeasure according to a preferred embodiment of the present invention isillustrated, wherein the tape measure, such as a conventional tapemeasure, comprises a tape casing 10 having a receiving cavity 11 and aguider opening 12 communicating with the receiving cavity 11, and aretraction unit 20 supported in the receiving cavity 11 of the tapecasing 10.

The tape measure further comprises a ruler blade 30, having an inner endattached to the retraction unit 20 and an outer end stopped at theguiding opening 12, adapted to slidably fold between a storage positionand a measuring position. In which, at the storage position, the rulerblade 30 is retracted to receive in the receiving cavity 11 in a coilflattened configuration manner via the retraction unit 20, and at themeasuring portion, the outer end 302 of the ruler blade 30 is slidablypulled to extend the ruler blade 30 in a concave-convex configurationout of the receiving cavity 11 through the guider opening 12.

The retraction unit 20 comprises a supporting reel 21 rotatablysupported in the receiving cavity 11 and a retraction element 22coaxially mounted to the supporting reel 21 to wind up the ruler blade30 in a coil-rolled manner about the supporting reel 21 at the storageposition. Accordingly, at normal condition, the ruler blade 30 is in aconcave-convex configuration that when the ruler blade 30 is extendedout of the tape housing 10. At the storage position, the ruler blade 30is retracted and pressed to flatten its shape by the retracting force ofthe retraction unit 20.

According to the preferred embodiment, the ruler blade 30 has alongitudinal central portion 31 and two longitudinal side portions 32integrally extended from two sides of the central portion 31 of theruler blade 30 respectively, wherein each of the side portions 32 of theruler blade 30 has a curvature smaller than a curvature of the centralportion 31 of the ruler blade 30, as shown in FIG. 3. In addition, ameasurement set is printed along at least one of the side portions 32 ofthe ruler blade 30.

The central portion 31 of the ruler blade 30 has a width W₁ in theconcave-convex configuration thereof having a dimension within a rangeof 20-22 mm, a height H₁ in the concave-convex configuration thereofhaving a dimension within a range of 3-4 mm.

The ruler blade 30 has a width W in the flattened configuration thereofhaving a dimension within the range of 40-42 mm, a height H in theconcave-convex configuration thereof having a dimension within the rangeof 9-12 mm, and a thickness T thereof having a dimension within a rangeof 1.15 mm-1.2 mm, such that the ruler blade 30 is capable of standingout from the tape casing 10 with a measuring length L at least 10 feetin a self-sustaining manner so as to prevent the ruler blade 30 frombuckling by its own weight. In addition, the width W₁ of the ruler blade30 in the concave-convex configuration has a dimension within the rangeof 32-36 mm.

The central portion 31 of the ruler blade 30 has a width W₂ in theconcave-convex configuration thereof having a dimension within the rangeof 20-22 mm, a height H₁ in the concave-convex configuration thereofhaving a dimension within the range of 3-4 mm.

As shown in FIGS. 3 and 4, the dimensions of the ruler blade 30 areillustrated that the width W of the ruler blade 30 in the flattenedconfiguration is 41.00 mm and the height H in the concave-convexconfiguration thereof is 11.34 mm. In addition, the width W₁ of theruler blade 30 in the concave-convex configuration is 32.11 mm.

According to the preferred embodiment, the curvature of the centralportion 31 of the ruler blade 30 is defined that the central projectingradius RI of the central portion 31 of the ruler blade 30 is 15 mm andthe central projecting angle α of the central portion 31 of the rulerblade 30 is 84⁰. In addition, the width W₂ of the central portion 31 ofthe ruler blade 30 in the concave-convex configuration is 20.07 mm andthe height H₁ of the central portion 31 of the ruler blade 30 in theconcave-convex configuration is 3.85 mm.

The curvature of each of the side portion 32 of the ruler blade 30 isdefined that the side projecting radius R₂ of the side portion 32 of theruler blade 30 is 30 mm and the side projecting angle θ of the sideportion 32 of the ruler blade 30 is 18.43⁰.

Accordingly, the central portion 31 of the ruler blade 30 is arranged tosupport the ruler blade 30 in such a manner that the ruler blade 30 isadapted to stand out from the tape casing 10 with the measuring length Lat least 10 feet in a self-sustaining manner so as to prevent the rulerblade 30 from buckling by its own weight. In addition, the curvature ofeach of the side portions 32 of the ruler blade 30 should be lesser thanthe curvature of the central portion 31 of the ruler blade 30 such thatthe measurement set printed along the respective side portion 32 of theruler blade 30 can be easily read when the ruler blade 30 is extended tostand out from the tape casing 10.

FIG. 5 illustrates the ruler blade 30 with alternative sets ofdimensions thereof such that the ruler blade 30 is capable of standingout from the tape casing 10 with a measuring length L at least 10 feetin a self-sustaining manner. The dimensions of the ruler blade 30,according to the first alternative mode, are illustrated that the widthW of the ruler blade 30 in the flattened configuration is 41.29 mm andthe height H in the concave-convex configuration thereof is 11.03 mm. Inaddition, the width W₁ of the ruler blade 30 in the concave-convexconfiguration is 32.94 mm.

The curvature of the central portion 31 of the ruler blade 30 is definedthat the central projecting radius R₁ of the central portion 31 of theruler blade 30 is 15 mm and the central projecting angle α of thecentral portion 31 of the ruler blade 30 is 84⁰. In addition, the widthW₂ of the central portion 31 of the ruler blade 30 in the concave-convexconfiguration is 20.07 mm and the height H₁ of the central portion 31 ofthe ruler blade 30 in the concave-convex configuration is 3.85 mm.

The curvature of each of the side portion 32 of the ruler blade 30 isdefined that the side projecting radius R₂ of the side portion 32 of theruler blade 30 is 45 mm and the side projecting angle θ of the sideportion 32 of the ruler blade 30 is 12.3⁰.

The dimensions of the ruler blade 30, according to the secondalternative mode, are illustrated that the width W of the ruler blade 30in the flattened configuration is 41.29 mm and the height H in theconcave-convex configuration thereof is 9.75 mm. In addition, the widthW₁ of the ruler blade 30 in the concave-convex configuration is 34.91mm.

The curvature of the central portion 31 of the ruler blade 30 is definedthat the central projecting radius R₁ of the central portion 31 of theruler blade 30 is 18 mm and the central projecting angle α of thecentral portion 31 of the ruler blade 30 is 74⁰. In addition, the widthW₂ of the central portion 31 of the ruler blade 30 in the concave-convexconfiguration is 21.67 mm and the height H₁ of the central portion 31 ofthe ruler blade 30 in the concave-convex configuration is 3.62 mm.

The curvature of each of the side portion 32 of the ruler blade 30 isdefined that the side projecting radius R₂ of the side portion 32 of theruler blade 30 is 45 mm and the side projecting angle θ of the sideportion 32 of the ruler blade 30 is 11.5⁰.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. It embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

1. A strengthened blade tape measure, comprising: a tape casing having areceiving cavity and a guider opening communicating with said receivingcavity; a retraction unit supported in said receiving cavity; and aruler blade, having an inner end attached to said retraction unit and anouter end stopped at said guiding opening, adapted to slidably foldbetween a storage position and a measuring position, wherein at saidstorage position, said ruler blade is retracted to receive in saidreceiving cavity in a coil flattened configuration manner via saidretraction unit, and at said measuring portion, said outer end of saidruler blade is slidably pulled to extend said ruler blade in aconcave-convex configuration out of said receiving cavity through saidguider opening, said ruler blade having a width in said flattenedconfiguration thereof having a dimension within a range of 40-42 mm, aheight in said concave-convex configuration thereof having a dimensionwithin a range of 9-12 mm, and a thickness thereof having a dimensionwithin a range of 1.15 mm-1.2 mm, such that said ruler blade is capableof standing out from said tape casing with a measuring length at least10 feet in a self-sustaining manner so as to prevent said ruler bladefrom buckling by its own weight.
 2. The strengthened blade tape measure,as recited in claim 1, wherein said width of said ruler blade in saidflattened configuration is 41.00 mm and said height of said ruler bladein said concave-convex configuration is 11.34 mm.
 3. The strengthenedblade tape measure, as recited in claim 1, wherein said width of saidruler blade in said flattened configuration is 41.29 mm and said heightof said ruler blade in said concave-convex configuration is 11.03 mm. 4.The strengthened blade tape measure, as recited in claim 1, whereinwherein said width of said ruler blade in said flattened configurationis 41.29 mm and said height of said ruler blade in said concave-convexconfiguration is 9.75 mm.
 5. The strengthened blade tape measure, asrecited in claim 1, wherein said ruler blade has a longitudinal centralportion and two longitudinal side portions integrally extended from twosides of said central portion of said ruler blade respectively, whereineach of said side portions of said ruler blade has a curvature smallerthan a curvature of said central portion of said ruler blade, whereinsaid central portion of said ruler blade has a width in saidconcave-convex configuration thereof having a dimension within a rangeof 20-22 mm, a height in said concave-convex configuration thereofhaving a dimension within a range of 3-4 mm.
 6. The strengthened bladetape measure, as recited in claim 2, wherein said ruler blade has alongitudinal central portion and two longitudinal side portionsintegrally extended from two sides of said central portion of said rulerblade respectively, wherein each of said side portions of said rulerblade has a curvature smaller than a curvature of said central portionof said ruler blade, wherein said central portion of said ruler bladehas a width in said concave-convex configuration thereof having adimension within a range of 20-22 mm, a height in said concave-convexconfiguration thereof having a dimension within a range of 3-4 mm. 7.The strengthened blade tape measure, as recited in claim 3, wherein saidruler blade has a longitudinal central portion and two longitudinal sideportions integrally extended from two sides of said central portion ofsaid ruler blade respectively, wherein each of said side portions ofsaid ruler blade has a curvature smaller than a curvature of saidcentral portion of said ruler blade, wherein said central portion ofsaid ruler blade has a width in said concave-convex configurationthereof having a dimension within a range of 20-22 mm, a height in saidconcave-convex configuration thereof having a dimension within a rangeof 3-4 mm.
 8. The strengthened blade tape measure, as recited in claim4, wherein said ruler blade has a longitudinal central portion and twolongitudinal side portions integrally extended from two sides of saidcentral portion of said ruler blade respectively, wherein each of saidside portions of said ruler blade has a curvature smaller than acurvature of said central portion of said ruler blade, wherein saidcentral portion of said ruler blade has a width in said concave-convexconfiguration thereof having a dimension within a range of 20-22 mm, aheight in said concave-convex configuration thereof having a dimensionwithin a range of 3-4 mm.
 9. The strengthened blade tape measure, asrecited in claim 5, wherein said curvature of said central portion ofsaid ruler blade is defined that a central projecting radius of saidcentral portion of said ruler blade is 15 mm and a central projectingangle of said central portion of said ruler blade is 84⁰, wherein saidcurvature of each of said side portion of said ruler blade is definedthat a side projecting radius of said side portion of said ruler bladeis 30 mm and a side projecting angle of said side portion of said rulerblade is 18.43⁰.
 10. The strengthened blade tape measure, as recited inclaim 6, wherein said curvature of said central portion of said rulerblade is defined that a central projecting radius of said centralportion of said ruler blade is 15 mm and a central projecting angle ofsaid central portion of said ruler blade is 84⁰, wherein said curvatureof each of said side portion of said ruler blade is defined that a sideprojecting radius of said side portion of said ruler blade is 30 mm anda side projecting angle of said side portion of said ruler blade is18.43⁰.
 11. The strengthened blade tape measure, as recited in claim 7,wherein said curvature of said central portion of said ruler blade isdefined that a central projecting radius of said central portion of saidruler blade is 15 mm and a central projecting angle of said centralportion of said ruler blade is 84⁰, wherein said curvature of each ofsaid side portion of said ruler blade is defined that a side projectingradius of said side portion of said ruler blade is 30 mm and a sideprojecting angle of said side portion of said ruler blade is 18.43⁰. 12.The strengthened blade tape measure, as recited in claim 8, wherein saidcurvature of said central portion of said ruler blade is defined that acentral projecting radius of said central portion of said ruler blade is15 mm and a central projecting angle of said central portion of saidruler blade is 84⁰, wherein said curvature of each of said side portionof said ruler blade is defined that a side projecting radius of saidside portion of said ruler blade is 30 mm and a side projecting angle ofsaid side portion of said ruler blade is 18.43⁰.
 13. The strengthenedblade tape measure, as recited in claim 5, wherein The strengthenedblade tape measure, as recited in claim 5, wherein said curvature ofsaid central portion of said ruler blade is defined that a centralprojecting radius of said central portion of said ruler blade is 15 mmand a central projecting angle of said central portion of said rulerblade is 84⁰, wherein said curvature of each of said side portion ofsaid ruler blade is defined that a side projecting radius of said sideportion of said ruler blade is 45mm and a side projecting angle of saidside portion of said ruler blade is 12.3⁰.
 14. The strengthened bladetape measure, as recited in claim 6, wherein said curvature of saidcentral portion of said ruler blade is defined that a central projectingradius of said central portion of said ruler blade is 15 mm and acentral projecting angle of said central portion of said ruler blade is84⁰, wherein said curvature of each of said side portion of said rulerblade is defined that a side projecting radius of said side portion ofsaid ruler blade is 45 mm and a side projecting angle of said sideportion of said ruler blade is 12.3⁰.
 15. The strengthened blade tapemeasure, as recited in claim 7, wherein said curvature of said centralportion of said ruler blade is defined that a central projecting radiusof said central portion of said ruler blade is 15 mm and a centralprojecting angle of said central portion of said ruler blade is 84⁰,wherein said curvature of each of said side portion of said ruler bladeis defined that a side projecting radius of said side portion of saidruler blade is 45 mm and a side projecting angle of said side portion ofsaid ruler blade is 12.3⁰.
 16. The strengthened blade tape measure, asrecited in claim 8, wherein said curvature of said central portion ofsaid ruler blade is defined that a central projecting radius of saidcentral portion of said ruler blade is 15 mm and a central projectingangle of said central portion of said ruler blade is 84⁰, wherein saidcurvature of each of said side portion of said ruler blade is definedthat a side projecting radius of said side portion of said ruler bladeis 45 mm and a side projecting angle of said side portion of said rulerblade is 12.3⁰.
 17. The strengthened blade tape measure, as recited inclaim 5, wherein said curvature of said central portion of said rulerblade is defined that a central projecting radius of said centralportion of said ruler blade is 18 mm and a central projecting angle ofsaid central portion of said ruler blade is 74⁰, wherein said curvatureof each of said side portion of said ruler blade is defined that a sideprojecting radius of said side portion of said ruler blade is 45 mm anda side projecting angle of said side portion of said ruler blade is11.5⁰.
 18. The strengthened blade tape measure, as recited in claim 6,wherein said curvature of said central portion of said ruler blade isdefined that a central projecting radius of said central portion of saidruler blade is 18 mm and a central projecting angle of said centralportion of said ruler blade is 74⁰, wherein said curvature of each ofsaid side portion of said ruler blade is defined that a side projectingradius of said side portion of said ruler blade is 45 mm and a sideprojecting angle of said side portion of said ruler blade is 11.5⁰. 19.The strengthened blade tape measure, as recited in claim 7, wherein saidcurvature of said central portion of said ruler blade is defined that acentral projecting radius of said central portion of said ruler blade is18 mm and a central projecting angle of said central portion of saidruler blade is 74⁰, wherein said curvature of each of said side portionof said ruler blade is defined that a side projecting radius of saidside portion of said ruler blade is 45 mm and a side projecting angle ofsaid side portion of said ruler blade is 11.5⁰.
 20. The strengthenedblade tape measure, as recited in claim 8, wherein said curvature ofsaid central portion of said ruler blade is defined that a centralprojecting radius of said central portion of said ruler blade is 18 mmand a central projecting angle of said central portion of said rulerblade is 74⁰, wherein said curvature of each of said side portion ofsaid ruler blade is defined that a side projecting radius of said sideportion of said ruler blade is 45 mm and a side projecting angle of saidside portion of said ruler blade is 11.5 ⁰.